مدیریت اکوسیستم های آبی ومنابع آب در شرایط وجود محرک های متعدد – مقدمه ای بر پروژه MARS  Managing aquatic ecosystems and water resources under multiple stress — An introduction to the MARS project

۱٫ Introduction Europe’s water resources and aquatic ecosystems are impacted by multiple stressors, which affect ecological and chemical status, water quantity and ecosystem functions and services. The relevance of multiple stressors differs regionally (EEA, 2012a): in Alpine and upland northern regions hydropower plants have fundamentally changed river and lake hydrology, morphology, sediment transport and connectivity, in lowland areas of Northern and Central Europe intensive agriculture and flood protection are important drivers of degradation, whilst Mediterranean catchments are impaired by riparian degradation and water scarcity and transitional and coastal waters are affected by eutrophication, pollution, morphological changes and different resource exploitation. In addition, climate change increases the risk of floods, erosion and pollution in wet regions and of droughts in water scarce regions (EEA, 2012b). According to Europe’s first River Basin Management Plans (RBMPs), 56% of European rivers, 44% of lakes, 25% of groundwater bodies and 70% of transitional waters failed to achieve the good status targets of the Water Framework Directive (WFD) (EEA, 2012a; ETC-ICM, 2012a). There are, however, strong regional differences: in Northern Europe and in some Eastern European and Mediterranean countries more than 40% of river water bodies are in high or good status, whilst in Central European countries, such as Belgium, the Netherlands and Germany, more than 80% failed to achieve the WFD quality targets. The reasons are manifold. Recent reports (EEA, 2012a; ETC-ICM, 2012a) list the most important pressures impacting individual water categories: only 19% of water bodies was not significantly impacted, whilst two pressures prevail: diffuse pollution (rivers: 45%, lakes: N30%) and hydromorphological degradation (rivers: N40%, lakes: N30%). Viewed in more detail, both diffuse pollution and hydromorphological degradation are composed of several individual components with complex interactions. Diffuse pollution mainly refers to increased nutrient loads and associated eutrophication effects, often in conjunction with fine sediment, pesticides and other toxic substances. Hydromorphological degradation is an even more vague term, including hydrological stress from low flows and water abstraction, flash floods, and morphological stress from barriers, straightening, bank fixation, removal of riparian vegetation and subsequent increase of water temperatures (ETC-ICM, 2012b). From this evidence, it is apparent that the causes of degradation of Europe’s waters are manifold and complex. Whilst single stressors such as strong organic pollution and acidification of freshwaters are declining and nowadays affecting just 14% and 10% of river water bodies, respectively (EEA, 2012a), Europe’s water bodies and water resources are now affected by a complex mixture of stressors resulting from urban and agricultural land use, hydropower generation and climate change (e.g. Stelzenmüller et al., 2010; Schinegger et al., 2012). Although the Programmes of Measures included in the RBMPs should reduce stressors and improve water body status, their potential to address increasingly complex, multiple stress situations is limited by current knowledge. A recent inventory of RBMPs for Germany revealed a strong focus on measures targeting single pressures such as point-source pollution and river continuity (Kail and Wolter, 2011). Under conditions of multiple stress, however, restoration actions may also initiate complex cause-effect chains of recovery, which are poorly understood (Feld et al., 2011). Overall, the first RBMPs have several problems: • Programmes of Measures are often decoupled from ecological assessment. • Although the majority of European water bodies are affected by more than one stressor, little is known about their combined effects. • For multiple-stress situations, simple dose–response relationships between stress intensity and biological effects based on empirical data are not sufficient for developing appropriate management measures. There is a need for improved process understanding of how multiple stressors affect degradation and restoration. • Besides the existing tools to assess water body status, tools are needed to prioritise measures and to predict ecological status following restoration. • The implementation of measures requires convincing arguments beyond the concept of ecological status, whose value is difficult for the public and policy makers to understand. Supplementary indicators targeting ecosystem functions, ecosystem services and human benefits are required. These are obstacles for the successful implementation of the WFD within the following set timeline: production of a 2nd version of the RBMPs in 2015, a 3rd version in 2021, and achievement of the overall WFD targets by 2027. A new stressor, climate change, is to be taken into account in the 2nd version. The planned revision of the WFD in 2019 offers an opportunity to advance its conceptual basis which is now almost 20 years old, and to consider the recent knowledge in addressing the WFD requirements (Hering et al., 2010). Major challenges for water resource management have emerged since the ratification of the WFD in 2000: New stressor combinations, including not least climate change, new pollutants, emerging pathogens and exploitation of the sub-surface for alternative forms of energy; more intense land use due to increased food prices and demand for biofuel; and increasingly diverging targets for food production, energy generation, water resource protection and biodiversity protection. The WFD is the core of Europe’s water policy, but there are several other relevant directives with manifold (and sometimes contrasting) approaches and targets. These include the Urban Waste Water Treatment Directive (91/271/EEC), the Nitrates Directive (91/676/EEC), the Bathing Water Directive (2006/7/EC), the Marine Strategy Framework Directive (2008/56/EC), the Habitats Directive (92/43/EEC), the Flood Risk Management Directive (2007/60/EC), the Strategy on Water Scarcity and Drought and the White Paper on Adaptation to Climate Change. The implementation of these policies to protect Europe’s water resources strongly interacts with other policy domains, such as the Renewable Energy Directive (2009/28/EC) and in particular with the Common Agricultural Policy. The Fitness Check of EU Freshwater Policy (http://ec.europa. eu/environment/water/blueprint/fitness_en.htm) outlines the strength of the current legislative framework, and also exposes conflicts with other EU policies and the weaknesses in its implementation. Problems identified include the incorporation of water quantity issues into RBMPs, including the definition of ecological flows (cf. environmental flows, Postel and Richter, 2003; Poff et al., 2010), land use impacts in particular from agriculture, climate change impacts, translation of the ecosystem services concept into practice, and insufficient dissemination and sharing of data. Implicit in all these issues is the need to address multiple stressors. The ecosystem services approach offers a powerful option to harness the efforts of all relevant partners (Ormerod, 2014). The Blueprint to Safeguard Europe’s Water Resources (http://ec. europa.eu/environment/water/blueprint/index_en.htm) describes 39 actions to strengthen the implementation of Europe’s water policies. Key amongst them are land use and ecological status, chemical status and pollution of EU waters, water efficiency, vulnerability of EU waters, and the need for cross-cutting problem solving and global aspects. Overall, the Blueprint provides a realistic assessment of achievements and problems of European water management, and embeds Europe’s water policy into a wider political context. As with the Fitness Check, it identifies complex stressors resulting from intense land-use and over-abstraction as key problems, and outlines solutions possible through other policy fields such as the Common Agricultural Policy. According to the Blueprint, the Common Implementation Strategy (CIS) of theWFD ensures its prominent role for European water policies. The EU-funded project MARS (Managing Aquatic ecosystems and water Resources under multiple Stress, www.mars-project.eu) addresses these challenges and is closely linked to the policy framework outlined above. This paper describes context, approaches and objectives of MARS and aims in particular to outline the conceptual model on which MARS is based and to describe the project’s approaches acting at three different scales.